This application is based on application No. 11-172565 filed in Japan, the content of which is hereby incorporated by reference.
1. Technical Field of the Invention
The present invention relates to a digital camera having a printing function.
2. Description of the Related Art
Of devices that use batteries as power sources, such as cameras (including a silver halide camera and a digital camera), those having battery checking functions are prevalent. A battery checking function is a judgment of whether a battery capacitance, required to operate the device, is present by measuring a voltage while current, required for the operation, flows. Since normal function/performance cannot be attained if the power-source voltage lowers, the device is so constructed as to perform normal operations by giving a warning or the like to the user in advance.
Conventionally, the user checks the battery, if necessary, by operating a button provided for battery checking. As microcomputers have been used more widely, however, automatic battery checking has been provided.
In a camera that performs automatic battery checking, as disclosed in Japanese Unexamined Patent Publication No. HEI 5-34383, a microcomputer is so constructed as to perform battery checking when, e.g., a main switch is turned ON, or when a release switch is half-pressed.
On the other hand, Japanese Unexamined Patent Publication No. HEI 3-29471 discloses a device comprising a digital camera integrally formed with a printer. In a so-called mobile-type structure that performs in-situ printing of shooting data, a battery is preferably used as the power source.
Such a digital camera with a printer requires different voltage levels depending on whether it is used as a camera or a printer. However, consideration has not been given to the different voltage levels in a conventional digital camera with a printer. As a matter of fact, a voltage level higher than that provided when the device is used as a camera is needed to drive the printer. In this case, however, a battery checking level determined uniformly might lead to the situation where a camera function cannot be used (unshootable) because of a level which is usable for the function as a digital camera but lower than a battery checking level for a printing function. There may also be the case where battery checking cannot be performed because of a level which is unusable for the printing function but higher than the battery checking level for the digital camera.
It is therefore an object of the present invention to provide a digital camera having a printing function which can perform a minimum function even when the voltage of a power source battery is lowered.
The present invention may include a digital camera having a printing function, which is driven by a battery, said digital camera comprising: a printer unit operable when a voltage of the battery is equal to or higher than a first voltage; a camera unit operable when the voltage of the battery is equal to or higher than a second voltage; a detector for detecting the voltage of the battery; and a controller for comparing the voltage of the battery, detected by the detector, with the first and second voltages and controlling respective operations of the printer unit and the camera unit based on the result of the comparison.
Thus, according to the present embodiment, the voltage judgment level is set for each of the printer unit and the camera unit. This makes it possible to not only enable or disable the operation of each of the printer unit and the camera unit but also enable the operation of either one of the printer unit and the camera unit and disable the operation of the other of the printer unit and the camera unit.
As a result, the minimum function can be performed even if the voltage of the power source battery is lowered.
In a further embodiment of the digital camera, the camera further comprises a selector for selecting either a function of the printer unit or a function of the camera unit. Preferably the controller compares a voltage required for the function selected by the selector with the voltage of the battery. More preferably, the controller compares the voltage of the battery with the first voltage when the printer unit is selected and the controller compares the voltage of the battery with the second voltage level when the camera unit is selected. Still preferably the camera further comprises an indicator for displaying the result of the control operation performed by the controller whereby the respective operations of the printer unit and the camera unit were enabled or disabled. Alternatively, the controller disables or enables the operation of either one of the printer unit selected or camera unit selected. Specifically, the controller performs the comparing operation or the control operation in synchronization with the camera unit performing a shooting preparation operation. More specifically, the controller performs the comparing operation or the control operation when the battery is replaced.
Other objects, features, and advantages of the invention will become apparent from the following description and from the claims.